This project is directed toward the developmental biology of the Myxobacterium, Myxococcus xanthus with special emphasis on cell interactions during aggregation and fruiting body formation. The particular aspects that will be studied are: 1) The role of outer membrane (OM) proteins in development. This will include a description of changes in OM proteins during development, using 2-D gel electrofocussing and electrophoresis, relating those changes to the various factors that induce development and attempting to isolate OM fractions that interfere with development. If the last approach progresses properly, we shall attempt to isolate corresponding OM receptor sites. 2) RNA synthesis during fruiting body formation will be studied. A 5-16S RNA fraction synthesized during development will be examined by means of hybridization competition and an in vitro translation system to check the hypothesis that the RNA is developmentally unique. Its stability will also be examined to determine if it is indeed more stable than average vegetative cell message. 3) Developing cells of phenotypically complementing mutants will be examined to characterize the extracellular signals that are exchanged during developmental autolysis. 4) Using a newly-developed slide culture technique, a variety of compounds will be screened for chemotactic attractiveness. Those that emerge will be examined more carefully on a stable gradient apparatus. We will attempt to determine the functional analogs of runs and tumbles. Attempts will be made to isolate motile, non-chemotactic mutants to examine the role of chemotaxis in development. A variety of approaches will be used to examine a new theory of gliding motility, i.e. that gradients of surface tension generated by the polar, regulated excretion of surfactants provide the motive force for gliding.